It is well known that there is a strong correlation among video image data, that is, there is a lot of redundant information. Inter-frame predictive encoding is to predict a current block to be encoded in order to obtain a predictive value by means of a block in a reference image that has been encoded in time domain, and then encode the difference between the value of the block to be encoded and the predictive value. Inter-frame predictive encoding typically includes forward prediction, backward prediction, symmetric prediction, and bidirectional prediction. The forward prediction or the backward prediction only require one forward or backward reference frame, while the symmetric prediction and the bidirectional prediction require both forward frame and backward reference frame.
Generally, in the video encoding framework of modern block-based motion compensation hybrid DCT transform, a weighting parameter of the bidirectional weighting may be considered to be (½, ½), then a forward weighting parameter is (1, 0) and a backward weighting parameter is (0, 1). In H.264 bidirectional encoding, separate encoding is used. For a block to be encoded of a frame to be encoded, for example, if there are three encoding parameters which are ½, ⅓, ¼, the forward reference frame and the backward reference frame of the block to be encoded correspond to three weighting parameters respectively and the weighting parameters of the forward reference frame and the backward reference frame will be selected from 9 (3*3) modes. In actual prediction processes, there may be cases where both the forward weighting parameter and the backward weighting parameter are ⅓. Obviously, such weighting parameters are unreasonable, which may cause low accuracy of inter-frame predictive encoding.